• Journal of Power Electronics
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• v.6 no.3
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• pp.226-234
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• 2006

Photovoltaic (PV) generators have nonlinear V-I characteristics and maximum power points which vary with illumination level and temperature. Using a maximum power point tracker (MPPT) with an intermediate converter can increase the system efficiency by matching the PV systems to the load. This paper presents a maximum power point tracker based on fuzzy logic and a control scheme for a single-phase inverter connected to the utility grid. The fuzzy logic controller (FLC) provides an adaptive nature for system performance. Also the FLC provides excellent features such as fast response, good performance and the ability to change the fuzzy parameters to improve the control system. A single-phase AC-DC inverter is used to connect the PV system to the grid utility and local loads. While a control scheme is implemented to inject the PV output power to the utility grid at unity power factor and reduced harmonic level. The simulation results have shown the effectiveness of the proposed scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.4
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• pp.553-558
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• 1998

We present in this paper the ture union bound of the performance of chip level detection for coded DS/CDMA system operating in Rician fading channels such as LEO satellite mobile radio where the maximum doppler frequency is very high. The main objective of this paper is to calculate the exact doe union bound of BER performance of different performance of different quadrature detectors and to find a optimum spreading factor as a function of fade rate. The rationale of using multiple chip detection is to reduce the effective fade rate or variation. We considered chip level differential detection, chip level maximum likelihood sequence estimation, noncoherent detection and coherent detection with perfect channel state information as a reference.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.89-92
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• 2008

The extreme heat watch warning system(EHWWS) that Korea Meterological Administration carried out a preliminary from July 1, 2007, considered both daily maximum temperature and daily maximum heat index simultaneously. It was requested revision of the standard level of EHWWS to solve the difficulty of forecasting occurred when we were considering two parameters simultaneously and we did not considering heat index according to areas. For this, we established three type standard, such as type 1 that considered both daily maximum temperature and daily maximum heat index, Under the extreme heat day that daily minimum temperature was more than $25^{\circ}C$, type 2 that considered daily maximum temperature and type 3 that considered only daily maximum heat index and then analyzed whether these 3 types satisfies the excess mortality of the extreme heat warning or not. As a results, type 1 and 2 were more explain away excess mortality each warning step than type 3. type 2 could also apply case of not to consider heat index according to areas and had a merit for extreme heat forecasting easily because the standard was simple. Therefore we think type 2 is more suitable and reasonable standard for Korea extreme heat watch warning system(KEHWWS) than type 1. In addition, we need to develop model that exactly predicts the excess mortality will be take place during the extreme heat warning and construct KEHWWS.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.2
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• pp.154-162
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• 2011

A reliability analysis model is developed for evaluating the crest freeboard of vertical breakwaters based on the concepts of maximum overtopping volume of individual wave. A reliability function is formulated by defining the margin of admissible overtopping volume and maximum overtopping volume that is depend on the number of overtopping waves, dimensionless crest freeboard, and mean overtopping discharge. In addition, Level III MCS technique is straightforwardly suggested by which the related empirical parameters to reliability function can be considered to be random variables with the wide range of different uncertainties. It can be possible to calculate the probabilities of failure according to the relative crest freeboard with the variations of the incident wave directions, the structural types of vertical breakwaters, and admissible overtopping volumes in conditions of the long and short crested-waves.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.393-403
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• 2008

The relationship between precipitation and groundwater level and the correlation between the moving average of precipitation and goundwater level were analyzed for the southern area of Korean peninsular. There were somewhat different patterns of seasonal fluctuation of groundwater level data. The groundwater level data tends to decrease in dry spell and increase in wet spell however the range between maximum and minimum values is quite different for each gauging point. The maximum correlation coefficient for each gauging station is obtained in a range of 20- to 130-day moving average period of precipitation. The critical infiltration, which is the maximum daily infiltration averaged throughout watershed, value is turned out to have the range of 10 to 90 mm and the moving average period is 10 to 150 days. We could have stronger correlation when we consider critical infiltration and modify the original precipitation data than we use original precipitation data.

• Microbiology and Biotechnology Letters
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• v.23 no.4
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• pp.472-478
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• 1995

Mycelial growth, color difference and productivity of red pigment of beni-koji by Monascus anka KCCM 11832 were examined with respect to it's pigment in submerged culture with various medium and culture conditions. Shaking incubation was more promoted mycelial growth and the production of pigments than that for non-shaking incubation, and red color became ten times deeper. The production of red pigment was the highest when incubated at 25$\circ$C for 7 days in pH 6.0, but mycelial growth was showed the highest at 32.5$\circ$C. The levels of carbon and nitrogen source for maximum red pigment production were 2% rice powder and 0.05% peptone, respectively and the level of peptone for maximum pigment production was lower than that for maximum mycelial growth. Among pigmentation promoting agents tested, MgSO$_{4}$, was found to be suitable for the production of red pigment, and the optimum level was 0.1%.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.1039-1040
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• 2006

In this study, we have been constructed measuring system for interference for TV broadcasting signals between Korea and Japan. In Busan, we have been measured 14 channel of Japan TV broadcasting signals during 4 days. The quality of image is that 2.5 level is maximum grade, and the quality of sound is that 3 level is maximum grade. And we have been observed Japan TV broadcasting signals, in Busan, Ulsan, and Pohang. There are detected 40 channels. The 19, 24, 29, 36, 39 channels have 3.0 grade image quality and The maximum field strength is $71dB{\mu}V$/m.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.05a
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• pp.247-251
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• 2002

In this paper the maximum current carrying capability of ACAs flip chip joint is investigated based on two failure mechanisms: (1) degradation of the interface between gold stud bumps and aluminum pads; and (2) ACA swelling between chips and substrates under high current stress. For the determination of the maximum allowable current, bias stressing was applied to ACAs flip chip joint. The current level at which current carrying capability is saturated is defined as the maximum allowable current. The degradation mechanism under high current stress was studied by in-situ monitoring of gold stud bump-aluminum pad ACA contact resistance and also ACA junction temperature at various current level. The cumulative failure distributions were used to predict the lifetime of ACAs flip chip joint under high current stressing. These experimental results can be used to better understand and to improve the current carrying capability of ACA flip chip joint.

• Structural Engineering and Mechanics
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• v.33 no.4
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• pp.529-537
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• 2009

A key parameter in the design of a laterally loaded pile is the determination of its performance level. Performance level of a pile is usually expressed as the maximum head deflection and bending moment. In general, uncertainties in the performance of a pile originates from many factors such as inherent variability of soil properties, inadequate soil exploration programs, errors taking place in the determination of soil parameters, limited calculation models as well as uncertainties in loads. This makes it difficult for practicing engineers to decide for the reliability of laterally loaded piles both in cohesive and cohesionless soils. In this paper, limit state functions and consequent performance functions are obtained for single concrete piles to predict the maximum bending moment, a widely accepted design criterion along with the permissible pile head displacement. Analyses were made utilizing three dimensional finite element method and soil-structure-interaction (SSI) effects were accounted for.

• Proceedings of the Korean Society for Quality Management Conference
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• 2009.10a
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• pp.317-323
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• 2009

In this paper, we propose new methods which is to determine level of noise factor. Even Taguchi give level of noise factor which is best(or maximum) and worst(or minimum) condition, we give level of noise factor which is representative value by observing noise factor frequency. Sometimes level of noise factor is given one, two and three. We know this method is more fit in real fields.